This invention relates to a system and a method for controlling an electric motor, and more particularly, to a system and a method that provide failure compensated motor control.
Increasing motor vehicle capacity, speed, and weight have steadily increased the risk of injury to occupants and pedestrians. A number of systems have been designed to provide occupant protection in the event of an accident. Active restraints, such as seat-belts, harnesses, and door locks restrain occupants in a vehicle, which minimizes their risk of being thrown within or from a vehicle.
Passive restraints also minimize the risks of injury and also do not require occupant activation. Air bags, for example, provide passive crash protection for vehicle occupants in a vehicle that collides with another object. An air bag inflates when a sensor, such as an accelerometer, detects a front-end or a side-impact collision. The sensor transmits an electric signal to an igniter that triggers a chemical reaction. The reaction inflates a cushion using an inflation gas to absorb the impact of the occupants as they are thrown against the cushion. Ports or vents within the cushion release the gas as the cushion absorbs the energy of the impact.
To perform well, an air bag must deploy quickly and forcefully to prevent occupants from striking the hard surfaces of the vehicle. The deployment force of the gas is greatest when the cushion is within two to three inches of an air bag cover. Optimally, occupants should be spaced from the undeployed air bag within a range of distances, but not closer than around 5 or 6 inches. Some occupants find it difficult to be positioned properly for comfort, visibility, and to access vehicle controls, and at the same time not be too close to the airbag. Recently, motor vehicle manufacturers have provided adjustable brake and accelerator pedals which are actuated by one or more electric motors. Since the proper operation of these actuators is important in providing the driver with access to critical vehicle controls, the systems must feature high reliability and tolerance to failures. Accordingly, there is a need for a failure resistant system for adjustable pedals that allows an operator to maintain a safe distance from the air bag cover. In addition, there are other vehicle systems utilizing electric motors in which failure resistance is a desirer feature.